Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
  • G01M3/00—Investigating fluid-tightness of structures
  • G01M3/02—Investigating fluid-tightness of structures by using fluid or vacuum
  • G01M3/04—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point
  • G01M3/20—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point using special tracer materials, e.g. dye, fluorescent material, radioactive material
  • G01M3/207—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point using special tracer materials, e.g. dye, fluorescent material, radioactive material calibration arrangements
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
  • G01M3/00—Investigating fluid-tightness of structures
  • G01M3/02—Investigating fluid-tightness of structures by using fluid or vacuum
  • G01M3/04—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point
  • G01M3/20—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point using special tracer materials, e.g. dye, fluorescent material, radioactive material
  • G01M3/202—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point using special tracer materials, e.g. dye, fluorescent material, radioactive material using mass spectrometer detection systems
  • G01M3/205—Accessories or associated equipment; Pump constructions

Definitions

• the invention relates to a gas passage with a selectively acting passage area.
• the invention also relates to methods for producing a passage surface for a selectively acting gas passage.
• Gas passages of this type are used, for example, in measuring or analysis devices. It should be achieved that light gases are preferred, heavier gases less preferred in e.g. enter a measuring device.
• DE-A-43 26 2665 discloses a leak detector whose test gas detector is equipped with a selective inlet system.
• Helium is used as the test gas.
• the selective inlet comprises a passage surface formed by a partition or a membrane, the permeability to helium of which is many decades higher than the permeability to other gases. This property has e.g. Quartz, quartz glass (SiO 2), pyrex glass or polymer membranes, e.g. from FEP.
• Measuring and analysis devices should generally have a high sensitivity and a short response time.
• the aim is to ensure that as much helium as possible passes through the passage area in the shortest possible time. This is only possible if the passage area is on the one hand as large as possible and on the other hand as thin as possible. This is opposed, however, by the fact that the passage area is generally subjected to a differential pressure.
• the interior of the measuring device is evacuated; outside there is atmospheric pressure. The size and the The thickness of the passage area is limited due to this differential pressure load.
• the present invention has for its object to provide a selectively acting gas inlet which can be acted upon with relatively large pressure differences and yet has a relatively large and relatively thin passage area.
• this object is achieved in that the selectively acting passage area is formed by a plurality of windows lying next to one another.
• the individual windows of the passage area are very small.
• 200 qua ⁇ dratician window made of quartz glass having an edge length of 0.7 mm are provided, then these form a overall Sammlung thoroughly stealsflache of 0.98 cm 2 - A füreriesflä ⁇ surface of this kind is already loaded then with a differential pressure of one atmosphere , if the thickness of the individual window surfaces is approximately 5 to 10 ⁇ m.
• the response time can be shortened and the gas throughput can be increased by heating a material.
• the planar arrangement makes it possible to apply thin-film metal structures to the windows as heating coils. This makes it possible to limit the heating to the individual windows. There is no risk that the glue points in the area will increasingly degas or leak.
• the windows forming the passage surface are preferably made of quartz, quartz glass or similar materials (e.g. Pyrex glass), since these are made using processes, as they are known from thin-film technology, can be manufactured at reasonable costs.
• FIG. 1 shows a pressure measuring device with a gas passage according to the invention
• Figure 2 is a plan view of the passage with a passage area consisting of 16 windows and
• FIGS. 3 and 4 are sketches for explaining the production of passage areas by methods as are known from thin-film technology.
• the passage according to the invention is generally designated 1. It is the passage to a vacuum measuring device 2 shown only as a symbol.
• the passage 1 comprises the flange 3, which serves to hold a disc 4.
• the pane 4 is equipped with a plurality of windows 5, which form the gas passage areas. Since the windows 5 are relatively small, the window-forming layers, membranes or the like can be very thin in order to be subjected to a certain differential pressure.
• the invention makes it possible to equip gas passages with relatively large but nevertheless relatively thin gas passage areas.
• quartz or quartz glass as the material for the passage areas or windows, since work of this material a variety of methods from semiconductor technology are known.
• a method of producing passages made of quartz glass is explained with reference to FIG. A silicon wafer 4 is assumed here. This is by an oxidation process with SiO ? coated (layers 6, 7 in FIG. 3 a). As a rule, this takes place in a mixture of water vapor and oxygen at temperatures around 1100 ° C and, depending on the process parameters, leads to oxide layer thicknesses of approx. 5 ⁇ m.
• the front and back of the Si wafers are passivated against the next process steps, for example with a 300nm thick PECVD-SiC layer.
• the window geometry and arrangement are then defined on the back of the Si wafer using a photolithography process.
• FIG. 4 Another method for producing gas-selective membranes is described in FIG. 4.
• a substrate 4 for. B. a silicon wafer, vacuum-tightly connected to another substrate 8 made of a gas-selective material, for example Pyrex glass, for example by anodic bonding (FIGS. 4a, b).
• the back of the substrate 4 is provided with a corresponding passivation 9, which can later be structured photolithographically.
• the gas-selective material is thinned down to a certain membrane thickness (FIG. 4c).
• a photolithography and etching process defines window openings on the back of the substrate 7 (FIG. 4d), which are then etched free in a further etching process (FIG. 4e).
• the window surfaces 5 made of quartz, quartz glass, pyrex glass or the like are expediently each equipped with a heating coil. This can be done using thin-film technology. Conductive material is applied using a vacuum coating process and structured in a meandering pattern in combination with a photolithography process, e.g. via a lift-off or an etching process.
• heating coils of this type are indicated and designated 10. The heating coils are electrically contacted (bonded) so that they can be switched on in a circuit. With this type of heating, each of the membranes can be brought to high temperatures (approximately 500 ° C.) selectively without heating the entire substrate 4. This prevents any existing adhesive connections, through which the disc 4 is connected to the flange 3, from heating up and degassing or becoming leaky. In addition, the power consumption is reduced and heating of the entire detection system is avoided.
• gas passage according to the invention is particularly expedient in the case of test gas detectors for leak detectors which work with light gases, preferably with helium as the test gas (see DE 43 26 265).
• analyzers for light gases H2, HD, D2, 3He, He etc.

Landscapes

• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Investigating Or Analysing Materials By Optical Means (AREA)
• Filtering Materials (AREA)
• Examining Or Testing Airtightness (AREA)
• Separation Using Semi-Permeable Membranes (AREA)
• Measuring Fluid Pressure (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (1)

Family

ID=7764139

Family Applications (1)

Country Status (6)

Cited By (3)

Families Citing this family (19)

Citations (5)

Family Cites Families (6)

• 1995
  • 1995-06-10 DE DE19521275A patent/DE19521275A1/de not_active Withdrawn
• 1996
  • 1996-06-01 EP EP96918657A patent/EP0831964B1/de not_active Expired - Lifetime
  • 1996-06-01 JP JP50256197A patent/JP3955323B2/ja not_active Expired - Fee Related
  • 1996-06-01 CN CN96194699A patent/CN1108851C/zh not_active Expired - Lifetime
  • 1996-06-01 DE DE59610940T patent/DE59610940D1/de not_active Expired - Lifetime
  • 1996-06-01 US US08/973,930 patent/US6277177B1/en not_active Expired - Lifetime
  • 1996-06-01 WO PCT/EP1996/002378 patent/WO1996041677A1/de active IP Right Grant

Patent Citations (5)

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